West Wall Portion of the Wastebed B/Harbor Brook IRM- March 2014

The West Wall IRM , located on the 90-acre Wastebed B/Harbor Brook site in the City of Syracuse and the Town of Geddes, addresses migration of site contaminants into Harbor Brook and Onondaga Lake.The West Wall portion of the site, is situated on an approximately 38-acre area bounded by Onondaga Lake to the north, I-690 to the south, Harbor Brook to the east, and the East Flume to the west.

The West Wall IRM construction was completed in accordance with the remedy selected by the NYSDEC in the Order on Consent dated November 25, 2003 and included the following components:

Installation of a sheet pile barrier wall from the eastern terminus of the Willis/Semet
Barrier Wall to the western bank of Lower Harbor Brook

Installation of a groundwater collection system along the barrier wall to achieve
hydraulic control

Grading and backfilling of portions of WBB and

Site restoration

The primary objective of the West Wall IRM is to contain contaminants in the shallow and intermediate groundwater regimes within the site. The sheet pile barrier wall serves to contain impacted soils and prevent migration of potentially contaminated groundwater and non-aqueous phase liquid (NAPL) to Onondaga Lake. The groundwater collection trench was constructed inboard of the sheet pile barrier wall. The trench captures impacted groundwater along the length of the wall from the shallow and intermediate hydrogeologic units. Groundwater is pumped to the Willis Avenue Groundwater Treatment Plant. The West Wall IRM construction also included backfill of the former Upper East Flume, which was required to complete installation of the
barrier wall.

The West Wall IRM is part of a larger hydraulic control system consisting of the Willis Avenue/Semet Tar Beds Sites (Willis/Semet) IRM and the Wastebed B/Harbor Brook IRM to address area groundwater. This system, which includes a sheet pile barrier wall along the Onondaga Lake shoreline and a groundwater collection system, was constructed in three phases beginning in 2006 and finishing in 2012. The system was designed and constructed to eliminate, to the extent practicable, the discharge of contaminated groundwater and NAPL to Onondaga Lake from the Southwest Shoreline area of Onondaga Lake. These IRMs were constructed consistent with the NYSDEC-approved designs. The system prevents the discharge of contaminated groundwater and NAPL to the lake from this area and has addressed the potential for groundwater upwelling to impact the Onondaga Lake sediment cap consistent with the cap design assumptions for this area.